Successional dynamics of species composition, functional traits and assembly mechanisms during the 60-year long history of agricultural transformations in subarctic tundra communities

Aims

Tundra communities are known for their harsh environmental conditions and tundra is one of the most vulnerable biomes on Earth. Restoring these unique communities after anthropogenic impact is crucial for the sustainable development of northern regions. The objective of this study was to evaluate the recovery of subarctic tundra after long-term agricultural use.

Location

Subarctic zone, European northeast, Vorkuta district, Komi Republic, Russia.

Methods

In the latter half of the twentieth century, large areas of tundra were plowed and cultivated with cereals to be used as fodder in livestock farms. These areas were subsequently abandoned (1990–2000) and the stage of natural recovery began. From 1960 to 2017 one of these plant communities was regularly assessed and we used these data, along with data from a reference tundra community, to examine changes in community assembly. We evaluated biodiversity indices, functional diversity using various plant traits and phylogenetic diversity.

Results

Agricultural management in tundra areas has led to the development of a meadow community that differs significantly from the typical tundra found in similar landscapes. The highest level of meadow biodiversity was observed under moderate anthropogenic pressure. The most significant changes in plant community assembly were observed after withdrawal from agricultural use. The average plant height, leaf area, and leaf dry matter content increased, while the average specific leaf area and leaf nitrogen content decreased. The functional and phylogenetic clustering was replaced by overdispersion.

Conclusions

Over the 20-year period following the cessation of agricultural use, we observed a decrease in the vitality of cultivated cereals and overall biodiversity. However, there was a redistribution of species abundance rather than a complete change in species composition. Deciduous and evergreen shrubs have not become introduced in sufficient abundance to transform the artificial meadow into the typical subarctic willow–shrub tundra. This is a fundamental difference between abandoned agricultural lands of the tundra zone and those of more southern regions, which are rapidly overgrown with pioneer tree or shrub species.